Higher Cognition

James H. Baños, Ph.D.

Department of Physical Medicine and Rehabilitation

Overview • • • General Organization and Recurring Themes A Closer Look at Organization Principles in Action: Domains of Cognition

General Organization

Where to begin?

• The “vertically organized” brain

Where to Begin?

• Major Dimensions of Organization: • • • Left vs. Right Anterior vs. Posterior Cortical vs. Subcortical

The Damaged and Undamaged Brain • Recurring Themes: • • • • Neural processing rarely occurs in a simple linear or sequential fashion Instead, it often occurs in continuous “loops” Like a water faucet that is always running Architecture is often hierarchical

The Damaged and Undamaged Brain • Recurring Themes • The nervous system thrives on balance and homeostasis of neural processes within these loops • • • Damage often upsets balance/homeostasis in a process A “normal” process runs unchecked or fails to run at all Like other neurologic symptoms, many neurocognitive symptoms can be thought of in “hyper” and “hypo” terms • Ex: muscle tone, reflexes, basal ganglia

A Closer Look at Organization

Left Vs. Right

Hemispheric Specialization

Hemispheric Specialization • Don’t think in terms of hemispheric “dominance”

Hemispheric Specialization • Left Hemisphere • • • • • Speech Reading/writing Praxis Verbal memory Processing detail • • • • • • • Right Hemisphere • • • Arousal Self-awareness Spatially directed attention Emotion/affect Nonverbal memory Visuospatial processing Processing “gestalt” Nonlanguage sound Music

Hemispheric Specialization • Left Hemisphere: “Classic” Clinical Presentation • • • Right hemiparesis Aphasia Apraxia

Hemispheric Specialization • Right Hemisphere: “Classic” Clinical Presentation • • • • • Left hemiparesis Poor arousal Left neglect Unawareness of deficits Flat affect

Anterior vs. Posterior

Anterior vs. Posterior

Anterior vs. Posterior • Posterior • • • • Processing of information about the environment Sensory gating Unimodal and multimodal sensory associations Constructing a unified “representation” of the environment across sensory modalities

Anterior vs. Posterior • Anterior • • Planning and formulating cognitive and behavioral goals Acting on hypothetical representations of the environment • Incorporating behavioral relevance, reinforcement value, and emotion into cognition and behavior

Cortical vs. Subcortical

Cortical vs. Subcortical • Subcortical structures • • • • Initiation Cessation Modulation Control

Cortical vs. Subcortical • Thalamus • • Not just a “sensory relay” Cortico-thalamo-cortical loops modulate: • • • Consciousness Arousal Vigilance “Cortical tone” • Foundation for higher attentional processes

Cortical vs. Subcortical • Basal ganglia • • • Initiation Cessation Maintenance • Similar role in motor and cognitive function

Cortical vs. Subcortical • Cortical-Basal Ganglionic Loops Motor Oculomotor Cortex SMA FEF Striatum Pallidum s. nigra Thalamus Putamen Vl-GPi Cl-SNr VLo VLm Caudate (body) Cdm-GPi Vl-SNr VAmc MDpl

Cortical vs. Subcortical Cortex Striatum Pallidum s. nigra Thalamus Dorsolateral Prefrontal DLPFC dl-Caudate (head) ldm-GPi vl-SNr VApc MDpc Lateral Orbitofrontal LOFC vm-Caudate (head) mdm-GPi rm-SNr VAmc MDmc Anterior Cingulate AC VS rl-GPi, VP rd-SNr pm-MD

Cortical vs. Subcortical • Basal Ganglia: Motor Symptoms • Hyperkinetic disorders (too much movement) • • • Slow writhing movements Quick jerking movements Repetitive abrupt movements • Hypokinetic disorder (too little movement) • Difficulty initiating motor movement • • • Motor impersistence Rigidity Reduced eyeblink

Cortical vs. Subcortical • Basal Ganglia: Cognitive Symptoms • • • • • • “hypercognitive” • Perseveration • Intrusion “Hypocognitive” Poor cognitive initiation Poor recall (failure to initiate recall processes) Loss of cognitive set (cognitive impersistence) Diminished semantic search effectiveness

Cortical vs. Subcortical • Basal Ganglia: Emotionally Guided Behavior • • “hyper” • Obsessive-compulsive behaviors • • Addiction, gambling Mania (in some disorders such as Huntington’s Disease) • Affective Lability “Hypo” • • Avolition Flat affect

Cortical vs. Subcortical • Cerebellum Cerebrocerebellum Feedback Plan Cortex Cerebellum Effectors “Reality”

Cortical vs. Subcortical • Cerebellar Signs • Motor • • Ataxia Dysmetria • Cognitive • • “Cognitive Ataxia” “Dysmetria of Thought” • Emotionally Guided Behavior • • Affective lability Psychiatric symptoms

Putting it Together… Common View: Cognition Motor/Sensory

Putting it Together… Reality: Purposeful Effortful Sensorimotor Cognition Emotionally Guided Behavior Automatic

Principles in Action: Domains of Cognition

Domains of Cognition • • • • Motor and Sensory Aspects of Cognition Language Attention Executive Function

Hierarchical Organization Multimodal Association Cortex Unimodal Association Primary Sensory

Hierarchical Organization Multimodal Association Somatosensory Association Primary Somatosensory Visual Association Primary Visual Auditory Association Primary Auditory

Hierarchical Organization Somatosensory visual auditory

Hierarchical Processing Premotor Anterior Posterior Multimodal Association Cortex Primary Motor SMA Unimodal Association Unimodal Association Unimodal Association Primary Somatosensory Primary Visual Primary Auditory

Motor and Sensory Aspects of Cognition Multimodal Association Cortex Premotor SMA Primary Motor Hemiparesis

Motor and Sensory Aspects of Cognition Multimodal Association Cortex Premotor SMA Primary Motor Akinesia, Bimanual dyscoordination

Motor and Sensory Aspects of Cognition Apraxia Cortex Premotor SMA Primary Motor

Motor and Sensory Aspects of Cognition • Apraxia - Inability to correctly perform learned skilled movements,

not

due to impaired basic motor function, impaired cognition, or impaired comprehension • Lesion: Inferior parietal lobule, corpus callosum, SMA

Motor and Sensory Aspects of Cognition Multimodal Association Cortex Multimodal Association Cortex Premotor SMA Primary Motor Corpus ?

Callosum Premotor Primary Motor SMA Alien Hand

Motor and Sensory Aspects of Cognition Multimodal Association Cortex Visual Association Somatosensory Association Auditory Association

Motor and Sensory Aspects of Cognition Multimodal Association Cortex ?

Visual Association Association Association Primary Visual Primary Somatosensory Primary Auditory

Motor and Sensory Aspects of Cognition • Agnosia -- Impairment of object recognition in the presence of relatively intact basic perception and language • • • • Visual Object Agnosia Prosopagnosia (agnosia for faces) Tactile Agnosia Auditory Agnosia

Motor and Sensory Aspects of Cognition Visual Association Somatosensory Association Auditory Association Primary Visual Primary Somatosensory Primary Auditory

Motor and Sensory Aspects of Cognition • • Hemispatial Neglect Visuospatial Integration Deficits

Motor and Sensory Aspects of Cognition

Language

Language

Language Association Cortex Broca’s Expressive (non-fluent) Association Cortex Language Association Wernicke’s Receptive (fluent) “Pure” Language

Language Association Cortex Broca’s Expressive (non-fluent) Association Cortex Language Association Wernicke’s Receptive (fluent) “Pure” Language

Language • Wernicke’s Aphasia • Fluent speech (but doesn’t make sense) • • Impaired comprehension Impaired repetition • Linguistic analog to a primary sensory deficit • Can’t decode words or associate meaning

Language Association Cortex Broca’s Expressive (non-fluent) Association Cortex Language Association Wernicke’s Receptive (fluent) “Pure” Language

Language • Broca’s Aphasia • Non-fluent speech • • Intact comprehension Impaired repetition • Linguistic analog to a primary motor deficit • Can’t produce the components of language output

Language Association Cortex Broca’s Expressive (non-fluent) Association Cortex Language Association Wernicke’s Receptive (fluent) “Pure” Language

Language • Transcortical Sensory Aphasia • • • Fluent Speech Impaired comprehension Intact repetition • Linguistic analog to agnosia • Can decode the word but can’t make associations to meaning

Language Association Cortex Broca’s Expressive (non-fluent) Association Cortex Language Association Wernicke’s Receptive (fluent) “Pure” Language

Language • Transcortical Motor Aphasia • • • Non-fluent speech Intact Comprehension Intact Repetition • Linguistic Analog to an Apraxia • Broca’s area can produce speech, but lacks associations necessary to assemble the components

Attention • • • “Attention” is a generic term Refers to a family of processes Attention is fluid and constantly changing

Attention • Aspects of Attention • Arousal • General level of responsivity • Orientation • Realignment of sensory organs • Selective Attention • Processing of one stimulus over another • Divided Attention • Simultaneous processing of stimuli • • Attention Span • Holding of information with rehearsal “Working Memory” • Mental manipulation of information in attention span

Attention • • Modulation of attention is an “anterior” function It is mediated by cortical basal ganglionic loops • Some attentional shifts are automatic • • • Some must be initiated and maintained Salience and relevance must be balanced Unwanted shifts must be inhibited (“stimulus pull”)

Executive Function • Dorsolateral Frontal • • • • • Planning/goal formation Organizing Sequencing Set shifting Abstract thinking • Orbital Frontal • • • • Inhibition Behavioral modulation Cognitive modulation Evaluating relevance/reward

Executive Function • Impaired initiation: • Failure to generate ideas/courses of action • Impaired inhibition: • • • Impulsive cognitive approach You think it, you do it You think it, you say it

Executive Function • Impaired set-shifting • • Perseveration/decreased mental flexibility Inability to shift to a more appropriate strategy when you get feedback that the current strategy is ineffective • Impaired Planning • • • • Difficulty sequencing multiple actions to achieve a goal Difficulty seeing more than one “move” ahead in the game Difficulty generating multiple “if-then” alternate courses of action Difficulty assessing consequences of various choices

Executive Function • Impaired Abstract Reasoning • • Literal or “concrete” thinking style More likely to think in terms of objects and actions rather than concepts

Executive Function • Executive Function is also… • “Personality” • Point of convergence for cognitive, emotional, and motivational aspects of behavior